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Status
Current state: DraftUnder Discussion
Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]
JIRA: here [Change the link from KAFKA-1 to your own ticket]
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
Describe the problems you are trying to solve.
Public Interfaces
Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.
A public interface is any change to the following:
Binary log format
The network protocol and api behavior
Any class in the public packages under clientsConfiguration, especially client configuration
org/apache/kafka/common/serialization
org/apache/kafka/common
org/apache/kafka/common/errors
org/apache/kafka/clients/producer
org/apache/kafka/clients/consumer (eventually, once stable)
Monitoring
Command line tools and arguments
- Anything else that will likely break existing users in some way when they upgrade
Proposed Changes
We all know that it is possible to listen to mutliple topics by using the kafka-console-consumer
CLI tool and using the --include
argument. While I find this functionality useful personally, there are no way to know from which topic the message came from. This is useful to me, especially during development of projects that publishes message to Kafka, and I don't see a way to do it, neither with kafka-console-consumer
nor with other 3rd party tools I know of. I find the change to be quite trivial, it's definitely helpful to me, and I wish that it helps others that may need it.
Public Interfaces
Currently --property
exists for printing extra information such as key
, headers
, partition
, etc...
This led me to propose adding –-property print.topic=true
to the kafka-console-consumer
tool.
Printing a message with the "print.topic" set to "true" would produce this output:
Topic:topic value
Printing a message with these properties:
"print.offset" -> "true"
"print.topic" -> "true"
"print.timestamp" -> "true"
"print.partition" -> "true"
"print.key" -> "true"
produces the following output:
NO_TIMESTAMP Partition:0 Offset:123 Topic:topic key value
Proposed Changes
Adding –property print.topics=true
would print the topic of the message. The
accessor already exists in the topic()
consumerRecord
objectDescribe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.
Compatibility, Deprecation, and Migration Plan
- What impact (if any) will there be on existing users?
- If we are changing behavior how will we phase out the older behavior?
- If we need special migration tools, describe them here.
- When will we remove the existing behavior?
Rejected Alternatives
No impact on existing user, as this change will only add a new –property print.topic=true
option in the kafka-console-consumer
tool.
Rejected Alternatives
-If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.